In the current optical fiber transmission networks, Automatic Protection Switching (APS) has become an important means in a network self-healing system. APS protocols of the optical fiber transmission networks, such as an APS protocol of a Synchronous Digital Hierarchy (SDH) and an APS protocol of an Optical Transport Network (OTN), are in the process of the continuous development and improvement.
In the APS protocol of the OTN, the description related to the receiving and maintaining of a switch control command includes: if one new switch control command is accepted, any switch control command with a lower priority preceding it will be discarded. If one switch control command with a higher priority covers alert information with a lower priority or an APS request in bidirectional switching, and other requests, such as the APS request in the bidirectional switching still exists when this switch control command with the higher priority is cleared, then this APS request will be reset to be valid. If one switch control command is covered by alert information or an APS request in the bidirectional switching, this switch control command will be discarded.
The above APS protocol only defines how to determine whether the switch control command is maintained or discarded after a network device receives the switch control command. It does not describe how to inform a user of the information regarding the discarding. However, in the practical operation process of the network device, the switch control command is often sent by a network manager. When other requests with higher priorities occur on the network device, for example a remote APS request is received in the bidirectional switching, and when the priority of this APS request is higher than that of the switch control command sent by the network manager, the switch control command on the network device will not be valid any more and will be discarded. However, the network manager usually is unable to know various trigger information of the protocol in real-time, and doesn't care about priority relationship of various information either. The data consistency between the network device and the network manager is unable to be maintained after the network device discards the switch control command. The solution often used at present is that the user manually performs a query and the network device feeds back the current state of the switch control command to the network manager.
In networks, such as the Ethernet (ETH), the Transport Multi Protocol Label Switching (TMPLS) network, etc., problems similar to those in the above optical network also exist.